1. Field of the Invention
The present invention relates to an ink composition, an ink set, and an inkjet image forming method.
2. Related Art
In recent years, as a result of ever-increasing demand for the protection of resources, the protection of the environment, the enhancement of operational stability, and the like, the conversion of inks into aqueous products is advancing. As in the case of oil-based inks, the qualities required in aqueous inks include fluidity, storage stability, glossiness of film, clarity, coloring ability, and the like. However, compared to oil-based vehicles, most pigments have a markedly poor adaptability to aqueous vehicles with respect to pigment dispersibility and the like and therefore, satisfactory quality cannot be obtained by conventional dispersion methods. The use of various additives, for example, aqueous pigment dispersion resins or surfactants, has hitherto been studied, but an aqueous ink that satisfies all the adaptation properties described above and is comparable to existing high quality oil-based inks has not been obtained.
In order to solve these problems, for example, an aqueous ink composition containing a pigment and colloidal silica has been disclosed (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2002-206063). Further, an ink composition containing a resin emulsion and an inorganic oxide colloid has been disclosed (see, for example, JP-A No. 2005-23102), and it is described that a good image can be formed.